DElirium and LIGHT: Exploring Modifiable Risk Factors of Delirium - a Pilot Study (DELIGHT-P)

August 24, 2026 updated by: King's College Hospital NHS Trust

After a period of critical illness many people develop problems with memory, attention and thinking and this can make daily life more difficult. A risk factor for these problems is delirium. Delirium is a sudden change in the brain that causes confusion and difficulty focusing. People develop delirium when they are sick for another reason, such as a severe infection, or after surgery. Other risk factors for delirium are altered sleep/wake cycle, and absence of daylight. While delirium is very common in critical care, it's difficult to recognise and the reasons why it happens are not fully understood.

There are no treatments for delirium. Management focusses on reducing the impact of things that make it more likely for someone to develop delirium. For example, by making sure pain is well controlled and that family members can visit. While it comes with its challenges, maintaining a normal day and night cycle by turning lights off and reducing the number of interruptions during nighttime hours is also a strategy used and research has shown that sometimes this works. Unfortunately, the findings are not the same in every study, and the reasons why these interventions work to reduce delirium are not explored.

This study, called DELIGHT-P, wants to look at the relationship between delirium and light exposure to help to understand why absence of daylight is a risk factor for delirium. We think it has something to do with changes in the 'body clock' of patients in critical care. To find this out we will collect blood samples, measure light levels at the bedside, and assess participants for delirium. After discharge from critical care we will see participants again and ask them about their memory and do some thinking tests. We will also do another blood test. The blood samples will be tested for markers of changes to the 'body clock' and others will be tested for proteins that might be useful for recognising when someone has delirium.

As this is a pilot study, the research will be done with fewer people taking part. This is to check that the things we want to measure are the right things, and that it's possible to do the research. We hope that in the future we can do a larger study to be able to draw conclusions about what we find. The findings from this study may help us understand how light exposure and an altered body clock contributes to developing delirium. By checking for proteins that might be present in patients who have delirium, it might help us understand what processes are happening in the body to cause delirium. It is possible that through this work, we can identify potential treatment targets for delirium.

We hope that by doing this, we may be able to improve some of the memory and thinking problems that people have after a stay in critical care.

Study Overview

Status

Recruiting

Detailed Description

Background:

Delirium is a neuropsychiatric syndrome characterised by acute deficits in attention and other aspects of cognition. Patients with delirium have altered arousal, often displaying signs of hypervigilance and agitation, or indeed reduced levels of consciousness that look like coma. Many experience troubling symptoms in the form of hallucinations or delusions. Delirium is associated with longer hospital stays, increased mortality and long term cognitive impairment.

Delirium is highly prevalent in acute hospital environments. In critical care, it is reported that up to 70% of patients have delirium. Despite this, the mechanisms underpinning its onset and persistence are poorly understood. Recent evidence suggests that disruption in circadian rhythms - through altered light exposure, noise and sleep disturbance - may play a role in it's pathophysiology. There have been few studies which have directly measured light intensity and quality within clinical settings and correlated this to markers of circadian disruption and explored how this interacts with delirium risk.

In recent years, markers of neuronal damage have shown promise in helping to detect delirium, and understand the pathophysiological mechanisms underpinning it, but more work is needed to explore their use in critically ill patients at risk of delirium.

DELIGHT-P (DElirium and LIGHT: Exploring modifiable risk factors and mechanisms of delirium - A Pilot Study) is a pilot for a prospective observational cohort study. This observational cohort study will describe patterns of light exposure, endocrine rhythms, and delirium incidence in critically ill patients.

Results from this programme of work will inform the design of a powered observational study and potentially future studies examining whether circadian based interventions can reduce delirium incidence and improve outcomes. Beyond the critical care environment, the findings will support specialties across the NHS where delirium is highly prevalent, as well as guide hospital and critical care design, informing evidence-based policies on light exposure and sleep promoting care.

Importantly, findings from this work may also elucidate some of the mechanisms of delirium, offering insight to what is currently a very challenging syndrome with significant consequences.

Primary Objective:

To assess the feasibility of carrying out a study that exploring modifiable risk factors of delirium. To do this we will assess the recruitment capability, retention rate and evaluate the data collection procedures.

Secondary Objectives

  • To explore the relationship between light exposure, altered circadian rhythms and delirium in critically ill patients.
  • To explore the association between serum markers of inflammation, neuronal damage and delirium
  • To explore the cognitive outcomes of critically ill patients and the relationship with markers of neuronal damage.

Study Type

Observational

Enrollment (Estimated)

10

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Adult patients in critical care

Description

Inclusion Criteria:

  • Adult patients >50 years old
  • Patients admitted to critical care in previous 24 hours
  • Patients with an arterial or venous access line suitable for blood sampling
  • Patients with an expected length of stay >36 hours

Exclusion Criteria:

  • Patients with a primary neurosurgical diagnosis
  • Patients with pre-existing cognitive impairment
  • Patients expected to die within 24 hours or receiving end of life treatment

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Patients in critical care
Patients receiving care in critical care

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Recruitment and retention
Time Frame: 6 months
6 months
Adherence to study procedures
Time Frame: 6 months
6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

August 1, 2026

Primary Completion (Estimated)

February 1, 2027

Study Completion (Estimated)

May 1, 2027

Study Registration Dates

First Submitted

August 24, 2026

First Submitted That Met QC Criteria

August 24, 2026

First Posted (Actual)

August 28, 2026

Study Record Updates

Last Update Posted (Actual)

August 28, 2026

Last Update Submitted That Met QC Criteria

August 24, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Subscribe